brcmfmac: make brcmf_of_probe more generic

We may want to use Open Firmware for other devices than just SDIO ones.
In future we may want to support more Broadcom properties so there is
really no reason for such limitation.

Call brcmf_of_probe for all kind of devices & move extra conditions to
the body of that funcion.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>